/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 * Module Info: This module contains the functionality for setting & querying
 *      the datatype offset for the H5T interface.
 */

#include "H5Tmodule.h"          /* This source code file is part of the H5T module */


#include "H5private.h"		/* Generic Functions			*/
#include "H5Eprivate.h"		/* Error handling		  	*/
#include "H5Iprivate.h"		/* IDs			  		*/
#include "H5Tpkg.h"		/* Datatypes				*/

/* Static local functions */
static herr_t H5T_set_offset(const H5T_t *dt, size_t offset);



/*-------------------------------------------------------------------------
 * Function:	H5Tget_offset
 *
 * Purpose:	Retrieves the bit offset of the first significant bit.	The
 *		significant bits of an atomic datum can be offset from the
 *		beginning of the memory for that datum by an amount of
 *		padding. The `offset' property specifies the number of bits
 *		of padding that appear to the "right of" the value.  That is,
 *		if we have a 32-bit datum with 16-bits of precision having
 *		the value 0x1122 then it will be laid out in memory as (from
 *		small byte address toward larger byte addresses):
 *
 *		    Big	     Big       Little	Little
 *		    Endian   Endian    Endian	Endian
 *		    offset=0 offset=16 offset=0 offset=16
 *
 *		0:  [ pad]   [0x11]    [0x22]	[ pad]
 *		1:  [ pad]   [0x22]    [0x11]	[ pad]
 *		2:  [0x11]   [ pad]    [ pad]	[0x22]
 *		3:  [0x22]   [ pad]    [ pad]	[0x11]
 *
 * Return:	Success:	The offset (non-negative)
 *		Failure:	Negative
 *
 * Programmer:	Robb Matzke
 *		Wednesday, January  7, 1998
 *
 *-------------------------------------------------------------------------
 */
int
H5Tget_offset(hid_t type_id)
{
    H5T_t	*dt;
    int	ret_value;

    FUNC_ENTER_API(-1)
    H5TRACE1("Is", "i", type_id);

    /* Check args */
    if(NULL == (dt = (H5T_t *)H5I_object_verify(type_id,H5I_DATATYPE)))
	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an atomic data type")

    /* Get offset */
    if((ret_value = H5T_get_offset(dt)) < 0)
	HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "cant't get offset for specified datatype")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Tget_offset() */


/*-------------------------------------------------------------------------
 * Function:	H5T_get_offset
 *
 * Purpose:	Retrieves the bit offset of the first significant bit.	The
 *		significant bits of an atomic datum can be offset from the
 *		beginning of the memory for that datum by an amount of
 *		padding. The `offset' property specifies the number of bits
 *		of padding that appear to the "right of" the value.  That is,
 *		if we have a 32-bit datum with 16-bits of precision having
 *		the value 0x1122 then it will be laid out in memory as (from
 *		small byte address toward larger byte addresses):
 *
 *		    Big	     Big       Little	Little
 *		    Endian   Endian    Endian	Endian
 *		    offset=0 offset=16 offset=0 offset=16
 *
 *		0:  [ pad]   [0x11]    [0x22]	[ pad]
 *		1:  [ pad]   [0x22]    [0x11]	[ pad]
 *		2:  [0x11]   [ pad]    [ pad]	[0x22]
 *		3:  [0x22]   [ pad]    [ pad]	[0x11]
 *
 * Return:	Success:	The offset (non-negative)
 *		Failure:	Negative
 *
 * Programmer:	Quincey Koziol
 *		Wednesday, October 17, 2007
 *
 *-------------------------------------------------------------------------
 */
int
H5T_get_offset(const H5T_t *dt)
{
    int	ret_value = -1;         /* Return value */

    FUNC_ENTER_NOAPI(-1)

    /* Defer to parent*/
    while(dt->shared->parent)
        dt = dt->shared->parent;
    if(!H5T_IS_ATOMIC(dt->shared))
	HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "operation not defined for specified data type")

    /* Offset */
    ret_value = (int)dt->shared->u.atomic.offset;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5T_get_offset() */


/*-------------------------------------------------------------------------
 * Function:	H5Tset_offset
 *
 * Purpose:	Sets the bit offset of the first significant bit.  The
 *		significant bits of an atomic datum can be offset from the
 *		beginning of the memory for that datum by an amount of
 *		padding. The `offset' property specifies the number of bits
 *		of padding that appear to the "right of" the value.  That is,
 *		if we have a 32-bit datum with 16-bits of precision having
 *		the value 0x1122 then it will be laid out in memory as (from
 *		small byte address toward larger byte addresses):
 *
 *		    Big	     Big       Little	Little
 *		    Endian   Endian    Endian	Endian
 *		    offset=0 offset=16 offset=0 offset=16
 *
 *		0:  [ pad]   [0x11]    [0x22]	[ pad]
 *		1:  [ pad]   [0x22]    [0x11]	[ pad]
 *		2:  [0x11]   [ pad]    [ pad]	[0x22]
 *		3:  [0x22]   [ pad]    [ pad]	[0x11]
 *
 *		If the offset is incremented then the total size is
 *		incremented also if necessary to prevent significant bits of
 *		the value from hanging over the edge of the data type.
 *
 *		The offset of an H5T_STRING cannot be set to anything but
 *		zero.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		Wednesday, January  7, 1998
 *
 * Modifications:
 * 	Robb Matzke, 22 Dec 1998
 *	Moved real work to a private function.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Tset_offset(hid_t type_id, size_t offset)
{
    H5T_t	*dt;
    herr_t      ret_value=SUCCEED;       /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE2("e", "iz", type_id, offset);

    /* Check args */
    if (NULL == (dt = (H5T_t *)H5I_object_verify(type_id,H5I_DATATYPE)))
	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an atomic data type")
    if (H5T_STATE_TRANSIENT!=dt->shared->state)
	HGOTO_ERROR(H5E_ARGS, H5E_CANTINIT, FAIL, "data type is read-only")
    if (H5T_STRING == dt->shared->type && offset != 0)
	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "offset must be zero for this type")
    if (H5T_ENUM==dt->shared->type && dt->shared->u.enumer.nmembs>0)
	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "operation not allowed after members are defined")
    if (H5T_COMPOUND==dt->shared->type || H5T_REFERENCE==dt->shared->type || H5T_OPAQUE==dt->shared->type)
	HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "operation not defined for this datatype")

    /* Do the real work */
    if (H5T_set_offset(dt, offset)<0)
	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to set offset")

done:
    FUNC_LEAVE_API(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5T_set_offset
 *
 * Purpose:	Sets the bit offset of the first significant bit.  The
 *		significant bits of an atomic datum can be offset from the
 *		beginning of the memory for that datum by an amount of
 *		padding. The `offset' property specifies the number of bits
 *		of padding that appear to the "right of" the value.  That is,
 *		if we have a 32-bit datum with 16-bits of precision having
 *		the value 0x1122 then it will be laid out in memory as (from
 *		small byte address toward larger byte addresses):
 *
 *		    Big	     Big       Little	Little
 *		    Endian   Endian    Endian	Endian
 *		    offset=0 offset=16 offset=0 offset=16
 *
 *		0:  [ pad]   [0x11]    [0x22]	[ pad]
 *		1:  [ pad]   [0x22]    [0x11]	[ pad]
 *		2:  [0x11]   [ pad]    [ pad]	[0x22]
 *		3:  [0x22]   [ pad]    [ pad]	[0x11]
 *
 *		If the offset is incremented then the total size is
 *		incremented also if necessary to prevent significant bits of
 *		the value from hanging over the edge of the data type.
 *
 *		The offset of an H5T_STRING cannot be set to anything but
 *		zero.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		Wednesday, January  7, 1998
 *
 * Modifications:
 * 	Robb Matzke, 22 Dec 1998
 *	Also works for derived data types.
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5T_set_offset(const H5T_t *dt, size_t offset)
{
    herr_t      ret_value=SUCCEED;       /* Return value */

    FUNC_ENTER_NOAPI(FAIL)

    /* Check args */
    HDassert(dt);
    HDassert(H5T_STRING!=dt->shared->type || 0==offset);
    HDassert(H5T_REFERENCE!=dt->shared->type);
    HDassert(H5T_OPAQUE!=dt->shared->type);
    HDassert(H5T_COMPOUND!=dt->shared->type);
    HDassert(!(H5T_ENUM==dt->shared->type && 0==dt->shared->u.enumer.nmembs));

    if (dt->shared->parent) {
	if (H5T_set_offset(dt->shared->parent, offset)<0)
	    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to set offset for base type")

        /* Adjust size of datatype appropriately */
        if(dt->shared->type==H5T_ARRAY)
            dt->shared->size = dt->shared->parent->shared->size * dt->shared->u.array.nelem;
        else if(dt->shared->type!=H5T_VLEN)
            dt->shared->size = dt->shared->parent->shared->size;
    } else {
        if (offset+dt->shared->u.atomic.prec > 8*dt->shared->size)
            dt->shared->size = (offset + dt->shared->u.atomic.prec + 7) / 8;
        dt->shared->u.atomic.offset = offset;
    }

done:
    FUNC_LEAVE_NOAPI(ret_value)
}

